During my second ward month as a medical intern, I admitted a middle-aged gentleman with a past history of well-controlled hypertension and diabetes mellitus who had experienced a first-time, ten-minute episode of substernal chest pain while mowing his lawn. The vast majority of “rule out myocardial infarction” hospitalizations on a non-Cardiology service last fewer than twenty-four hours: once acute, life-threatening diagnoses such as acute coronary syndrome and pneumonia have been excluded, most illnesses are easily managed with medications and close outpatient followup. However, this man’s echocardiogram revealed a disturbing finding: his aortic valve was severely narrowed, although it had been reportedly normal on a similar study two years earlier. This disease, aortic stenosis, results in progressive obstruction of the outflow of oxygenated blood from the heart to the rest of the body. Common symptoms of fatigue, difficulty breathing with exertion, or chest discomfort may not be apparent early in the development of the disease, but the narrowing of the valve can progress rapidly and ultimately precipitate the death of half of untreated individuals within two years of detection. Fortunately, this gentleman was fit and healthy enough to tolerate surgical replacement of his aortic valve, but almost one-third of patients are not so lucky.
The New England Journal of Medicine has recently published a study by Leon et al. that highlights a new treatment for patients with aortic stenosis who are not eligible for surgical intervention due to medical comorbidities: transcatheter aortic valve implantation (TAVI). The procedure involves the intravenous insertion of a folded bioprosthetic valve and the subsequent unfurling and placement of that valve using catheter-based techniques. (View a video illustrating the procedure.) The 179 patients who received TAVI had a reduced all-cause mortality rate of 30.7% at one year as compared to 50.7% in the control group treated with standard therapy including balloon valvuloplasty. Notably, while standard therapy does not reduce the overall mortality rate of patients with aortic stenosis, TAVI has a survival benefit. In addition, patients treated with TAVI had fewer hospitalizations and reduced symptoms according the New York Heart Association (NYHA) classification. However, patients who were treated with TAVI also experienced more strokes, major bleeding, and vascular complications. At 30 days, 5.0% of patients treated with TAVI had suffered major strokes (as defined as a score of 2 or higher on the modified Rankin scale) as compared to 1.1% of patients receiving standard therapy.
Transcatheter aortic valve implantation offers an imperfect but compelling option for treatment in patients who otherwise would have no treatments that could alter the course of this disease. Dr. Harold L. Lazar, a cardiothoracic surgeon at Boston Medical Center, notes in his accompanying editorial: “Now that there are evidence-based clinical data to substantiate the benefits of TAVI in patients who are not suitable candidates for surgery, there will be a temptation to expand this technology to all patients with aortic stenosis.” At this time, however, surgical aortic valve replacement remains the standard of care in most patients.
How do you currently manage severe aortic stenosis in patients who are not eligible for surgical replacement? Is this study enough evidence for you to advocate the selection of this procedure for these patients in your practice?